In the recovery of oil from a subterranean hydrocarbon-bearing formation, it is possible to recover only a portion of the oil in the formation using primary recovery methods that utilize the natural formation pressure to produce the oil. A portion of the oil that cannot be produced from the formation using primary recovery methods may be produced by improved or enhanced oil recovery (EOR) methods. Improved oil recovery methods include waterflooding.
Typically, further oil is produced from the formation after primary recovery by injecting water into the formation to mobilize oil for production from the formation. The injected water may drive a portion of the oil in the formation to a well for production from the formation. Oil not produced from the formation may be trapped within pores in the formation by capillary action of water extending across the pore throats of the pores. As a result, a significant quantity of oil located in the portions of the formation may be left in the formation and not recovered by the waterflood.
Improvements to methods of recovering oil from a hydrocarbon-bearing formation including those having oil trapped by water within pores of the formation are desirable.